The roller is an important part of the belt conveyor used in coal transportation. Due to the harsh environment of coal mines, the rollers are in a state of high load and high friction for a long ...time, which causes wear failure and has a serious impact on the reliability and safety of the equipment. In order to prepare roller material with excellent bearing performance and friction performance, CF/PUE composites were prepared by pouring method with polyurethane as the matrix and carbon fiber as reinforcement. Due to the low surface activity of unmodified carbon fibers and poor bonding performance with the matrix, MoSsub.2 was generated on the surface of carbon fiber by the in situ generation method in this paper. It was found that the mechanical properties of MoSsub.2/CF/PUE composites were better when the CF content was 0.3 wt%. The Shore hardness reached 92.2 HA, which is 10% higher than pure polyurethane. The tensile strength was 38.44 MPa, which is 53% higher than pure polyurethane. The elongation at break was 850%, which is 16% higher than pure polyurethane. The maximum compressive stress was 2.32 MPa, which is 42% higher than pure polyurethane. The friction coefficient was much lower than that of pure PUE composites, the friction coefficient was 0.284, which is 59% lower than pure polyurethane.
In the present work, the functionalisation of austenitic stainless steel, AISI 316L surfaces via nanosecond Nd:YAG laser texturing in order to modify the surface morphology with crosshatch and dimple ...patterns is presented. A tribological analysis under lubrication with sunflower and jojoba oil with and without the addition of a solid lubricant, MoSsub.2 nanotubes, was performed. In conjunction with friction/wear response laser-textured surface wettability, oil spreadability and oil retention capacity were also analysed. It was shown that the crosshatch pattern generally exhibited lower friction than the dimple pattern, with the addition of MoSsub.2 nanotubes not having any significant effect on the coefficient of friction under the investigated contact conditions. This was found in addition to the better oil spreadability and oil retention capacity results of the crosshatch-textured surface. Furthermore, texturing reduced the wear of the stainless-steel surfaces but led to an approximately one order of magnitude larger wear rate of the steel counter-body, primarily due to the presence of hard bulges around the textured patterns. Overall, the crosshatch pattern showed better oil retention capacity and lower friction in combination with different vegetable oils, thus making it a promising choice for improving tribological performance in various environmentally friendly applications.
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•The MAX phase Ti2SnC enhances iron-based self-lubricant composites mechanical properties.•Ti2SnC addition improves mechanical strength but reduces ultimate compressive ...strength.•Graphite addition synergizes with Ti2SnC, lowering the friction coefficient and wear rate.
This work focuses on developing novel iron-based self-lubricating composites reinforced with Ti2SnC MAX phase produced by powder metallurgy. Two amounts of Ti2SnC (5 and 10 vol%) and the addition of 10 vol% graphite were evaluated. The microstructure revealed a partial reaction between the matrix and the Ti2SnC, exhibiting a degree of dissociation in the presence of graphite, leading to the precipitation of carbides. The addition of the MAX phase significantly improved the hardness and compression strength. The dry coefficient of friction was around 0.12 for Fe + 5Ti2SnC + 10Gr, showing a remarkable reduction in wear rate up to 85 % compared to pure iron. The results demonstrate a synergistic effect between the MAX phase and graphite, enhancing tribological performance and wear resistance.
Based on the advantage of rapid net-shape fabrication, laser powder bed fusion (LPBF) is utilized to process Bsub.4C-reinforced Ti composites. The effect of volumetric energy density (VED) on the ...relative density, microstructural evolution, tensile properties and wear behaviors of Bsub.4C-reinforced Ti composites were systematically investigated. The LPBF-ed samples with high relative density (>99%) can be achieved, while the pores and un-melted powders can be observed in the sample owing to the low energy input (33 J/mmsup.3). The additive particulates Bsub.4C were transformed into needle-like TiB whiskers with nano-scale while C dissolved in the Ti matrix. Fine-scale grains (<10 μm) with random crystallographic orientation can be achieved and the residual stress shows a downtrend as the VED increases. Through the analysis of the tensile and wear tests, the sample at 61 J/mmsup.3VED showed a good combination of strength and wear performance, with an ultimate tensile strength of 951 MPa and a wear rate of 3.91 × 10sup.−4 mmsup.3·Nsup.−1msup.−1. The microstructural evolution in VED changes and the corresponding underlying strengthening mechanisms of LPBF-ed Ti + Bsub.4C composites are conducted in detail.
To enhance the tribological performance of the conventional TiCrN coating, the MoSsub.2–TiCr coatings are deposited onto the TiCrN layer by magnetron sputtering. In general, the MoSsub.2 is ...implemented to enhance the friction reduction performance of the TiCrN coating, while the Ti and Cr are doped to increase the density of the structure and prevent MoSsub.2 from oxidizing. The results reveal that with an increase in the content of Ti and Cr in the MoSsub.2–TiCr top layer, the hardness and the coating–substrate adhesion force of the composite coating increase, respectively, due to the compact top layer. Further, the optimized Ti and Cr doping in the MoSsub.2 top layer greatly enhances the tribological properties of the TiCrN/MoSsub.2–TiCr composite coating with a friction coefficient as low as 0.06 and the wear rate is only 6% of the TiCrN coating. The main reason for the excellent tribological properties of the TiCrN/MoSsub.2–TiCr composite coating is probably due to the recrystallization of the MoSsub.2 in the process of wear.
In this article, engineering surface application is introduced as a new concept. The basis of this concept is the understanding that different surface technologies are applied to design of existing ...engineering components but, it is necessary to know that surface engineering would cover only part of the design of the component, the surface treatment to be applied should also be known. This is because, surfaces with a high index of hardening due to deformation, are resistant to severe adhesive wear, abrasion and pickling, but they should not have the same resistance to other types of wear. It means that a correlation must be established between the surface quality and the pickling resistance. In this article, it is shown that the use of high compatibility metallic materials is preferred and that a correlation can be established between the surface quality and the pickling resistance by a simple number. The selection of materials and the methods of obtaining the engineering surfaces for tribological applications, depends to a large extent on the mechanism and particular type of predominant wear. Therefore, the selection of materials resistant to wear will be analyzed depending on the type of wear in question.
Laser cladding Ni60/2.0 wt.%CeOsub.2 self-lubricating anti-wear composite coatings on 35CrMoV steel were thermally treated at 25 °C, 500 °C, 600 °C and 700 °C for 1 h, respectively. The macroscopic ...morphology of composite coatings was characterized by optical microscopy. The evolution of microstructure was studied by scanning electron microscopy. The precipitated phase of the coating was analyzed by X-ray diffractometer. The microhardness and wear properties of the composite coatings were measured by microhardness tester and friction and wear test. The effects of thermal treatment and no thermal treatment on the mechanical properties of the composite coatings were systematically studied by the above experiments. The experimental analysis shows that the main phase composition of Ni60/2.0 wt.%CeOsub.2 composite coating is γ-(Ni, Fe), Crsub.7Csub.3, Crsub.23Csub.6, CrB, CrFeB and Crsub.2Nisub.3. Meanwhile, in XRD, it can be seen that the diffraction peak has shifted to the left and the single diffraction peak is decomposed into double diffraction peaks with the thermal treatment at 700 °C, which indicates that the lattice in the coating phase has a certain distortion. Compared with the coatings without thermal treatment, Ni60 cladding layer has more uniform solute distribution and a denser and more uniform structure after thermal treatment at 700 °C. The laser cladding anti-wear composite coating demonstrates that the wear resistance performance shows the greatest improvement after thermal treatment at 700 °C.
In preparing MoSsub.2-based coatings by magnetron sputtering, the working pressure of the vacuum chamber directly affects the number and kinetic energy of sputtering particles, which causes a ...difference in coatings structure and performance. In this paper, MoSsub.2 composite coatings with Ce and Ti binary doping were prepared by unbalanced magnetron sputtering technology, and the variation of composition, structure, and tribological properties of Ce-Ti/MoSsub.2 coatings under different working pressures was studied. The results demonstrated that Ce and Ti doping improves pure MoSsub.2 coatings. The Ce-Ti/MoSsub.2 coatings reached the hardness of 9.02 GPa and the friction coefficient of 0.065 when working pressure was at 0.6 Pa. It was also observed that the deposition efficiency and wear rate reached the optimal value at 0.9 Pa. With the increase of working pressure, the columnar structure of the coating was coarse due to the change of kinetic energy and quantity of particles in the chamber. The intensity of the MoSsub.2 (002) diffraction peak decreased, which eventually led to a poor lubrication effect and aggravated wear. This study provides technical guidance for preparing metal-doped MoSsub.2 composite coatings with excellent mechanical and tribological properties.
Alsub.xCoCrFeNiTi (x = 0.1, 0.3, 0.6, 1) powders were prepared via mechanical alloying and were used as binders for SPS-produced Ti(C,N)-based cermets. The effects of AlxCoCrFeNiTi binder on phase ...composition, morphology, room-temperature mechanical properties, and oxidation resistance of cermets were studied. The research showed that cermets with Alsub.xCoCrFeNiTi binders exhibited a more homogeneous core-rim structure than cermets with cobalt binders. The Vickers hardness and fracture toughness of cermets with Alsub.xCoCrFeNiTi binders increased with the aluminum molar ratio due to the grain refinement and solid solution strengthening effect of carbonitrides. After static oxidation at 1000 °C, the mass gain of the cermets with Alsub.xCoCrFeNiTi binders changed according to a quasi-parabolic law, and the lowest mass gain was obtained in the cermet with Alsub.0.6CoCrFeNiTi binder. The oxidation kinetics curve of the benchmark cermet with cobalt followed a linear law. The oxidation product of Ti(C,N)-based cermet with cobalt was rich in TiOsub.2, and the Ti(C,N)-based cermets with Alsub.xCoCrFeNiTi binders were transformed into complex oxides, such as NiMoOsub.4, NiWOsub.4, FeMoOsub.4, Fesub.3Tisub.3Osub.9, and Nisub.3TiOsub.7. The oxide layer on the cermet with Alsub.0.6CoCrFeNiTi appeared to be dense and protective, which inhibited the diffusion of oxygen into the cermet and improved the oxidation resistance of the final product.
